Concentration-dependent response to pioglitazone in nonalcoholic steatohepatitis

Current Progress and Challenges in the Development of Pharmacotherapy for Metabolic Dysfunction-Associated Steatohepatitis

Metabolic dysfunction-associated steatohepatitis (MASH), a severe form of metabolic dysfunction-associated steatotic liver disease (MASLD), poses a significant threat to global health. Despite extensive research efforts over the past decade, only one drug has received market approval under accelerated pathways. In this review, we summarise the pathogenesis of MASH and present a comprehensive overview of recent advances in phase 2-3 clinical trials targeting MASH. These trials have highlighted considerable challenges, including low response rates to drugs, limitations of current surrogate histological endpoints, and inadequacies in the design of MASH clinical trials, all of which hinder the progress of MASH pharmacotherapy. We also explored the potential of non-invasive tests to enhance clinical trial design. Furthermore, given the strong association between MASLD and cardiometabolic disorders, we advocate for an integrated approach to disease management to improve overall patient outcomes. Continued investigation into the mechanisms and pharmacology of combination therapies may offer valuable insights for developing innovative MASH treatments.

Diabetes as a risk factor for MASH progression

Non-alcoholic (now: metabolic) steatohepatitis (MASH) is the progressive inflammatory form of metabolic dysfunction-associated steatotic liver disease (MASLD), which often coexists and mutually interacts with type 2 diabetes (T2D), resulting in worse hepatic and cardiovascular outcomes. Understanding the intricate mechanisms of diabetes-related MASH progression is crucial for effective therapeutic strategies. This review delineates the multifaceted pathways involved in this interplay and explores potential therapeutic implications. The synergy between adipose tissue, gut microbiota, and hepatic alterations plays a pivotal role in disease progression. Adipose tissue dysfunction, particularly in the visceral depot, coupled with dysbiosis in the gut microbiota, exacerbates hepatic injury and insulin resistance. Hepatic lipid accumulation, oxidative stress, and endoplasmic reticulum stress further potentiate inflammation and fibrosis, contributing to disease severity. Dietary modification with weight reduction and exercise prove crucial in managing T2D-related MASH. Additionally, various well-known but also novel anti-hyperglycemic medications exhibit potential in reducing liver lipid content and, in some cases, improving MASH histology. Therapies targeting incretin receptors show promise in managing T2D-related MASH, while thyroid hormone receptor-β agonism has proven effective as a treatment of MASH and fibrosis.

A consensus statement from the Japan Diabetes Society: A proposed algorithm for pharmacotherapy in people with type 2 diabetes - 2nd edition (English version)

This algorithm was issued for the appropriate use of drugs for the treatment of type 2 diabetes mellitus in Japan. The revisions include safety considerations, fatty liver disease as a comorbidity to be taken into account and the position of tirzepatide.

A consensus statement from the Japan Diabetes Society (JDS): a proposed algorithm for pharmacotherapy in people with type 2 diabetes-2nd Edition (English version)

The Japan Diabetes Society (JDS) adopted a sweeping decision to release consensus statements on relevant issues in diabetes management that require updating from time to time and launched a "JDS Committee on Consensus Statement Development." In March 2020, the committee's first consensus statement on "Medical Nutrition Therapy and Dietary Counseling for People with Diabetes" was published. In September 2022, a second consensus "algorithm for pharmacotherapy in people with type 2 diabetes" was proposed. In developing an algorithm for diabetes pharmacotherapy in people with type 2 diabetes, the working concept was that priority should be given to selecting such medications as would appropriately address the diabetes pathology in each patient while simultaneously weighing the available evidence for these medications and the prescribing patterns in clinical practice in Japan. These consensus statements are intended to present the committee's take on diabetes management in Japan, based on the evidence currently available for each of the issues addressed. It is thus hoped that practicing diabetologists will not fail to consult these statements to provide the best available practice in their respective clinical settings. Given that the persistent dual GIP/GLP-1 receptor agonist tirzepatide was approved in April 2023, these consensus statements have been revised1). In this revision, specifically, tirzepatide was added to the end of [likely involving insulin resistance] of "Obese patients" in Step 1: "Select medications to address the diabetes pathology involved" in Fig. 2. While the sentence, "Insulin insufficiency and resistance can be assessed by referring to the various indices listed in the JDS 'Guide to Diabetes Management.' was mentioned in the previous edition as well, "While insulin resistance is analogized based on BMI, abdominal obesity, and visceral fat accumulation, an assessment of indicators (e.g., HOMA-IR) is desirable" was added as information in order to more accurately recognize the pathology. Regarding Step 2: "Give due consideration to safety," "For renal excretion" was added to the "Rule of thumb 2: Avoid glinides in patients with renal impairment." The order of the medications in "rule of thumb 3: Avoid thiazolidinediones and biguanides in patients with heart failure (in whom they are contraindicated)." to thiazolidinediones then biguanides. In the description of the lowest part of Fig. 2, for each patient failing to achieve his/her HbA1c control goal, "while reverting to step 1" was changed to "while reverting to the opening" and "including reassessment if the patient is indicated for insulin therapy" was added. In the separate table, the column for tirzepatides was added, while the two items, "Characteristic side effects" and "Persistence of effect" were added to the area of interest. The revision also carried additional descriptions of the figure and table such as tirzepatides and "Characteristic side effects" in the statement, and while not mentioned in the proposed algorithm figure, nonalcoholic fatty liver disease (NAFLD) is covered from this revision for patients with comorbidities calling for medical attention. Moreover, detailed information was added to the relative/absolute indication for insulin therapy, the Kumamoto Declaration 2013 for glycemic targets, and glycemic targets for older people with diabetes. Again, in this revision, it is hoped that the algorithm presented here will not only contribute to improved diabetes management in Japan, but will continue to evolve into a better algorithm over time, reflecting new evidence as it becomes available.

Physiologically Based Pharmacokinetic (PBPK) Model Predictions of Disease Mediated Changes in Drug Disposition in Patients with Nonalcoholic Fatty Liver Disease (NAFLD)

PURPOSE

This study was designed to verify a virtual population representing patients with nonalcoholic fatty liver disease (NAFLD) to support the implementation of a physiologically based pharmacokinetic (PBPK) modeling approach for prediction of disease-related changes in drug pharmacokinetics.

METHODS

A virtual NAFLD patient population was developed in GastroPlus (v.9.8.2) by accounting for pathophysiological changes associated with the disease and proteomics-informed alterations in the abundance of metabolizing enzymes and transporters pertinent to drug disposition. The NAFLD population model was verified using exemplar drugs where elimination is influenced predominantly by cytochrome P450 (CYP) enzymes (chlorzoxazone, caffeine, midazolam, pioglitazone) or by transporters (rosuvastatin, 11C-metformin, morphine and the glucuronide metabolite of morphine).

RESULTS

PBPK model predictions of plasma concentrations of all the selected drugs and hepatic radioactivity levels of 11C-metformin were consistent with the clinically-observed data. Importantly, the PBPK simulations using the virtual NAFLD population model provided reliable estimates of the extent of changes in key pharmacokinetic parameters for the exemplar drugs, with mean predicted ratios (NAFLD patients divided by healthy individuals) within 0.80- to 1.25-fold of the clinically-reported values, except for midazolam (prediction-fold difference of 0.72).

CONCLUSION

A virtual NAFLD population model within the PBPK framework was successfully developed with good predictive capability of estimating disease-related changes in drug pharmacokinetics. This supports the use of a PBPK modeling approach for prediction of the pharmacokinetics of new investigational or repurposed drugs in patients with NAFLD and may help inform dose adjustments for drugs commonly used to treat comorbidities in this patient population.

A gut microbial metabolite of linoleic acid ameliorates liver fibrosis by inhibiting TGF-β signaling in hepatic stellate cells

The antidiabetic drug pioglitazone ameliorates insulin resistance by activating the transcription factor PPARγ. In addition to its blood glucose-lowering action, pioglitazone exerts pleiotropic effects including amelioration of nonalcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH). The mechanism by which pioglitazone achieves this latter effect has remained unclear, however. We here show that pioglitazone administration increases the amount of linoleic acid (LA) metabolites in adipose tissue of KK-Ay mice. These metabolites are produced by lactic acid bacteria in the gut, and pioglitazone also increased the fraction of Lactobacillus in the gut microbiota. Administration of the LA metabolite HYA (10-hydroxy-cis-12-octadecenoic acid) to C57BL/6 J mice fed a high-fat diet improved liver histology including steatosis, inflammatory cell infiltration, and fibrosis. Gene ontology analysis of RNA-sequencing data for the liver revealed that the top category for genes downregulated by HYA treatment was related to extracellular matrix, and the expression of individual genes related to fibrosis was confirmed to be attenuated by HYA treatment. Mechanistically, HYA suppressed TGF-β-induced Smad3 phosphorylation and fibrosis-related gene expression in human hepatic stellate cells (LX-2). Our results implicate LA metabolites in the mechanism by which pioglitazone ameliorates liver fibrosis, and they suggest that HYA is a potential therapeutic for NAFLD/NASH.

Efficacy of 3 months of additional pioglitazone treatment in type 2 diabetes patients with alcoholic fatty liver disease

Pioglitazone ameliorates liver dysfunction in type 2 diabetes (T2D) patients with non-alcoholic fatty liver disease (NAFLD); however, its efficacy in T2D patients with alcoholic fatty liver disease (AFLD) is unclear. Here, we conducted a retrospective single-center trial investigating whether pioglitazone ameliorates liver dysfunction in T2D patients with AFLD. T2D patients (n = 100) receiving 3 months of additional pioglitazone were divided into those with or without fatty liver (FL), and those with FL were further classified into AFLD (n = 21) and NAFLD (n = 57) groups. The effects of pioglitazone were compared across groups using medical record data on body weight changes; HbA1c, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and gamma-glutamyl transpeptidase (γ-GTP) levels; and fibrosis-4 (FIB-4) index. The pioglitazone dose (mean dose: 10.6 ± 4.6 mg/day) did not affect weight gain but significantly decreased the HbA1c level in patients with or without FL (P < 0.01 and P < 0.05, respectively). The decrease in HbA1c level was significantly more pronounced in patients with FL than in those without FL (P < 0.05). In patients with FL, the HbA1c, AST, ALT, and γ-GTP levels significantly decreased after pioglitazone treatment than before (P < 0.01). The AST and ALT levels, but not the γ-GTP level, and the FIB-4 index significantly decreased after pioglitazone addition in the AFLD group, similar to that in the NAFLD group (P < 0.05 and P < 0.01, respectively). Similar effects were observed following low-dose pioglitazone treatment (≤ 7.5 mg/day) (P < 0.05) in T2D patients with AFLD and NAFLD. These results suggest that pioglitazone may be also an effective treatment option for T2D patients with AFLD.

Considerations for Physiologically Based Modeling in Liver Disease: From Nonalcoholic Fatty Liver (NAFL) to Nonalcoholic Steatohepatitis (NASH)

Nonalcoholic fatty liver disease (NAFLD), representing a clinical spectrum ranging from nonalcoholic fatty liver (NAFL) to nonalcoholic steatohepatitis (NASH), is rapidly evolving into a global pandemic. Patients with NAFLD are burdened with high rates of metabolic syndrome-related comorbidities resulting in polypharmacy. Therefore, it is crucial to gain a better understanding of NAFLD-mediated changes in drug disposition and efficacy/toxicity. Despite extensive clinical pharmacokinetic data in cirrhosis, current knowledge concerning pharmacokinetic alterations in NAFLD, particularly at different stages of disease progression, is relatively limited. In vitro-to-in vivo extrapolation coupled with physiologically based pharmacokinetic and pharmacodynamic (IVIVE-PBPK/PD) modeling offers a promising approach for optimizing pharmacologic predictions while refining and reducing clinical studies in this population. Use of IVIVE-PBPK to predict intra-organ drug concentrations at pharmacologically relevant sites of action is particularly advantageous when it can be linked to pharmacodynamic effects. Quantitative systems pharmacology/toxicology (QSP/QST) modeling can be used to translate pharmacokinetic and pharmacodynamic data from PBPK/PD models into clinically relevant predictions of drug response and toxicity. In this review, a detailed summary of NAFLD-mediated alterations in human physiology relevant to drug absorption, distribution, metabolism, and excretion (ADME) is provided. The application of literature-derived physiologic parameters and ADME-associated protein abundance data to inform virtual NAFLD population development and facilitate PBPK/PD, QSP, and QST predictions is discussed along with current limitations of these methodologies and knowledge gaps. The proposed methodologic framework offers great potential for meaningful prediction of pharmacological outcomes in patients with NAFLD and can inform both drug development and clinical practice for this population.

Emerging therapeutic approaches for the treatment of NAFLD and type 2 diabetes mellitus

Non-alcoholic fatty liver disease (NAFLD) has emerged as the most prevalent liver disease in the world, yet there are still no approved pharmacological therapies to prevent or treat this condition. NAFLD encompasses a spectrum of severity, ranging from simple steatosis to non-alcoholic steatohepatitis (NASH). Although NASH is linked to an increased risk of hepatocellular carcinoma and cirrhosis and has now become the leading cause of liver failure-related transplantation, the majority of patients with NASH will ultimately die as a result of complications of type 2 diabetes mellitus (T2DM) and cardiometabolic diseases. Importantly, NAFLD is closely linked to obesity and tightly interrelated with insulin resistance and T2DM. Thus, targeting these interconnected conditions and taking a holistic attitude to the treatment of metabolic disease could prove to be a very beneficial approach. This Review will explore the latest relevant literature and discuss the ongoing therapeutic options for NAFLD focused on targeting intermediary metabolism, insulin resistance and T2DM to remedy the global health burden of these diseases.

The Role of Lipid Sensing Nuclear Receptors (PPARs and LXR) and Metabolic Lipases in Obesity, Diabetes and NAFLD

Obesity and type 2 diabetes mellitus (T2DM) are metabolic disorders characterized by metabolic inflexibility with multiple pathological organ manifestations, including non-alcoholic fatty liver disease (NAFLD). Nuclear receptors are ligand-dependent transcription factors with a multifaceted role in controlling many metabolic activities, such as regulation of genes involved in lipid and glucose metabolism and modulation of inflammatory genes. The activity of nuclear receptors is key in maintaining metabolic flexibility. Their activity depends on the availability of endogenous ligands, like fatty acids or oxysterols, and their derivatives produced by the catabolic action of metabolic lipases, most of which are under the control of nuclear receptors. For example, adipose triglyceride lipase (ATGL) is activated by peroxisome proliferator-activated receptor γ (PPARγ) and conversely releases fatty acids as ligands for PPARα, therefore, demonstrating the interdependency of nuclear receptors and lipases. The diverse biological functions and importance of nuclear receptors in metabolic syndrome and NAFLD has led to substantial effort to target them therapeutically. This review summarizes recent findings on the roles of lipases and selected nuclear receptors, PPARs, and liver X receptor (LXR) in obesity, diabetes, and NAFLD.

Gender differences in the efficacy of pioglitazone treatment in nonalcoholic fatty liver disease patients with abnormal glucose metabolism

Background

Pioglitazone is a promising therapeutic method for nonalcoholic fatty liver disease (NAFLD) patients with or without type 2 diabetes. However, there is remarkable variability in treatment response. We analyzed our previous randomized controlled trial to examine the effects of gender and other factors on the efficacy of pioglitazone in treating Chinese nonalcoholic fatty liver disease (NAFLD) patients with abnormal glucose metabolism.

Methods

This is a post hoc analysis of a previous randomized, parallel controlled, open-label clinical trial (RCT) with an original purpose of evaluating the efficacy of berberine and pioglitazone on NAFLD. The total population (n = 185) was randomly divided into three groups: lifestyle intervention (LSI), LSI + pioglitazone (PGZ) 15 mg qd, and LSI + berberine (BBR) 0.5 g tid, respectively, for 16 weeks. The study used proton magnetic resonance spectroscopy (¹H-MRS) to assess liver fat content.

Results

As compared with LSI, PGZ + LSI treatment further decreased liver fat content in women (− 15.24% ± 14.54% vs. − 8.76% ± 13.49%, p = 0.025), but less decreased liver fat content in men (− 9.95% ± 15.18% vs. − 12.64% ± 17.78%, p = 0.046). There was a significant interaction between gender and efficacy of pioglitazone before and after adjustment for age, smoking, drinking, baseline BMI, BMI change, treatment adherence, baseline liver fat content, and glucose metabolism.

Conclusion

The study recommends pioglitazone plus lifestyle intervention for Chinese NAFLD female patients with abnormal glucose metabolism.

Trial registration

Role of Pioglitazone and Berberine in Treatment of Non-Alcoholic Fatty Liver Disease, NCT00633282. Registered on 3 March 2008, https://register.clinicaltrials.gov.

What Are the Current Pharmacological Therapies for Nonalcoholic Fatty Liver Disease?

Of the currently available drugs tested to treat nonalcoholic fatty liver disease (NAFLD), the most efficacious drugs are pioglitazone (an insulin sensitizer) and vitamin E (an antioxidant). By targeting insulin resistance, the key pathogenic mechanism underlying metabolic syndrome and NAFLD, pioglitazone maybe the preferred drug to treat NAFLD. As we await the results of research trials into multiple new drugs to treat NAFLD, when should we use the currently available patients to treat NAFLD at the present time? To date, no drug has been approved by regulatory agency specifically to treat NAFLD. However, many drugs have been approved to treat other components of metabolic syndrome such as diabetes mellitus and dyslipidemia. Are we underutilizing the currently available drugs to treat NAFLD? Herein, we review the benefits and concerns of the use of these currently available drugs to treat NAFLD and suggest clinical scenarios, wherein the clinician should consider using these drugs.

Magnesium isoglycyrrhizinate ameliorates high fructose-induced liver fibrosis in rat by increasing miR-375-3p to suppress JAK2/STAT3 pathway and TGF-β1/Smad signaling

Increasing evidence has demonstrated that excessive fructose intake induces liver fibrosis. Epithelial-mesenchymal transition (EMT) driven by transforming growth factor-β1 (TGF-β1)/mothers against decapentaplegic homolog (Smad) signaling activation promotes the occurrence and development of liver fibrosis. Magnesium isoglycyrrhizinate is clinically used as a hepatoprotective agent to treat liver fibrosis, but its underlying molecular mechanism has not been identified. Using a rat model, we found that high fructose intake reduced microRNA (miR)-375-3p expression and activated the janus-activating kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) cascade and TGF-β1/Smad signaling, which is consistent with the EMT and liver fibrosis. To further verify these observations, BRL-3A cells and/or primary rat hepatocytes were exposed to high fructose and/or transfected with a miR-375-3p mimic or inhibitor or treated with a JAK2 inhibitor, and we found that the low expression of miR-375-3p could induce the JAK2/STAT3 pathway to activate TGF-β1/Smad signaling and promote the EMT. Magnesium isoglycyrrhizinate was found to ameliorate high fructose-induced EMT and liver fibrosis in rats. More importantly, magnesium isoglycyrrhizinate increased miR-375-3p expression to suppress the JAK2/STAT3 pathway and TGF-β1/Smad signaling in these animal and cell models. This study provides evidence showing that magnesium isoglycyrrhizinate attenuates liver fibrosis associated with a high fructose diet.

Treatment options for nonalcoholic fatty liver disease: a double-blinded randomized placebo-controlled trial

INTRODUCTION

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease worldwide and is becoming the most frequent indication of liver transplantation. Cardiovascular disease is the main cause of death in these patients. There is no Food and Drug Association-approved medication for NAFLD patients. We aimed to provide more robust evidence on the use of medications that are inexpensive and available, namely, metformin, silymarin, pioglitazone, and vitamin E, for treating NAFLD.

MATERIALS AND METHODS

We conducted a randomized double-blinded, placebo-controlled trial on 150 consecutive patients with NAFLD who were assigned to five groups: lifestyle plus placebo, metformin 500 mg/day, silymarin 140 mg/day, pioglithasone 15 mg/day, and vitamin E 400 IU/day, all for 3 months. Anthropometric and biochemical variables were measured at baseline and 3 months later.

RESULTS

The mean age of the patients was 47.0±9.1 (range: 18-65) years and the sex distribution was 73 (48.7%) women and 77 (51.3%) men. Patients in all groups showed a significant improvement in anthropometric parameters such as waist circumference and BMI. There was no statistically significant difference in alanine transaminase and aspartate transaminase in the control group after treatment (P=0.51, 0.18, respectively); however, both liver enzymes decreased significantly in the other groups.

DISCUSSION AND CONCLUSION

This randomized double-blinded placebo-controlled clinical trial suggested a significant benefit of silymarin, pioglitazone, and vitamin E in improving liver aminotransferases in patients with NAFLD after only 3 months, without exerting any specific side effects.

Treating Hepatic Steatosis and Fibrosis by Modulating Mitochondrial Pyruvate Metabolism

A hepatic comorbidity of metabolic syndrome, known as nonalcoholic fatty liver disease (NAFLD), is increasing in prevalence in conjunction with the pandemics of obesity and diabetes. The spectrum of NAFLD ranges from simple hepatic fat accumulation to a more severe disease termed nonalcoholic steatohepatitis (NASH), involving inflammation, hepatocyte death, and fibrosis. Importantly, NASH is linked to a much higher risk of cirrhosis, liver failure, and hepatocellular carcinoma, as well as an increased risk for nonhepatic malignancies and cardiovascular disease. Interest in the understanding of the disease processes and search for treatments for the spectrum of NAFLD-NASH has increased exponentially, but there are no approved pharmacologic therapies. In this review, we discuss the existing literature supporting insulin-sensitizing thiazolidinedione compounds as potential drug candidates for the treatment of NASH. In addition, we put these results into new context by summarizing recent studies suggesting these compounds alter mitochondrial metabolism by binding and inhibiting the mitochondrial pyruvate carrier.

A Genetic Score Associates With Pioglitazone Response in Patients With Non-alcoholic Steatohepatitis

Pioglitazone is used effectively to treat non-alcoholic steatohepatitis (NASH), but there is marked variability in response. This study examined whether genetic variation contributes to pioglitazone response variability in patients with NASH. This genetic substudy includes 55 participants of a randomized controlled trial designed to determine the efficacy of long-term pioglitazone treatment in patients with NASH. The primary outcome of the clinical trial was defined as ≥2-point reduction in the non-alcoholic fatty liver disease activity score (NAS). In this substudy, single nucleotide polymorphisms (SNPs) in putative candidate genes were tested for association with primary and secondary outcomes. A genetic response score was constructed based on the sum of response alleles for selected genes. The genetic response score was significantly associated with achievement of the primary outcome (odds ratio 1.74; 95% CI 1.27–2.54; p = 0.0015). ADORA1 rs903361 associated with resolution of NASH (p = 0.0005) and change in the ballooning score among Caucasian and Hispanic patients (p = 0.0005). LPL rs10099160 was significantly associated with change in ALT (p = 0.0005). The CYP2C8^∗3 allele, which confers faster pioglitazone clearance in allele carriers, was associated with change in fibrosis score (p = 0.026). This study identified key genetic factors that explain some of the inter-individual variability in response to pioglitazone among patients with NASH.